Conventional GPS receiver is a stand-alone receiver device providing GPS locations only to the local user. Traditionally, this GPS device can only receive the GPS satellite signals and compute its positions in an outdoor signal strength level, no aiding/assisted-GPS (A-GPS) information such as the satellite ephemeris and GPS clock data are needed or obtained. In other words, conventional GPS receiver is operational only outdoors. In order to provide both outdoor and indoor locations, high sensitivity GPS circuits, the so-called “indoor GPS” receiver, is recently available on the market for testing purposes. What's different from the conventional GPS receiver is that this indoor-capable GPS receiver uses A-GPS information provided externally by an external device to assist the satellite acquisitions for indoor location computation. This “indoor GPS”, or indoor-capable GPS receiver, is operational both indoors and outdoors.
Today's portable personal computer (PC), personal data assistant (PDA), microprocessor-based device can be used as an external device to deliver the A-GPS information to the “indoor GPS” unit if they can obtain the dynamic A-GPS information in real-time. However, under indoor operating environment, A-GPS information can only be obtained either from the wireless network through wireless protocol standards, or from a designated A-GPS server through the wireless data link. Unless the portable PC, PDA or microprocessor-based device is wireless Internet-capable, there is no way to make A-GPS information available to the indoor-capable GPS receiver as of today.
On the other hand, the so called “enhanced 911 (E911)-enabled”, “web-enabled”, “Internet-capable”, “Internet-ready”, or “high speed packet data-capable” cellular handsets, wireless PDAs and wireless portable PCs, are designed to be general purposed mobile devices. When a local user needs to know his/her location, these devices always require human interfaces and operations to initiate a wireless Internet connection and a GPS location request. In all non-E911 occasions, even equipped with the A-GPS information retrieval and GPS location positioning capabilities, these mobile devices always require the user to interact with the keypad and LCD in order to obtain his/her present location, at least during initial setup. In most cases, a location service fee will be charged to the user for each location request or as part of the location service option fee.
For wireless remote user location-tracking purposes, some conventional GPS receivers have been connected or integrated with microprocessor-based devices along with wireless data modems to transmit the remote user locations to a designate server. Most of these systems use wireless short message service (SMS) or paging services to transmit GPS locations, resulting in time delays ranging from a fraction of a minute to an hour when arriving at a designated remote server. Some systems use wireless voice-based data transfer technology with data being carried on a dedicated voice channel. The delay period has been reduced but heavy air traffic usage and expensive phone bills incurred. None of the microprocessor-based devices in these systems are capable of retrieving, organizing, and transferring A-GPS information automatically therefore their GPS receiver can not provide indoor locations, even though the packet data wireless modems might have been used.
In remote GPS location tracking applications where both indoor and outdoor areas must be covered, there exists no dedicated, separate, attachable, and automatic dedicated device to be used in conjunction with a packet data wireless modem for supplying always-connected, up-to-the-minute, Internet packet data-based indoor-capable GPS locations. It is therefore necessary to come up with an invention to address this issue. Furthermore, we know that transmitting packet data-based GPS locations via a wireless Internet network consumes air link and network resources. For example, a total of 10 megabytes of packet data is approximately equivalent to 180 web pages or 1,700 emails—according to data published by VoiceStream Wireless Corporation. In order to conserve the air data payload and to save the operating cost, a method of using User Datagram Protocol (UDP) to transmit GPS locations over the wireless Internet network is implemented in this invention. Since the UDP protocol adds no reliability, flow control, or error recovery schemes to the GPS location reporting in the broadcast mode, it is estimated that the air link traffic and Internet network usage will be greatly reduced.